The menopause transition is characterized by changes in energy expenditure and body composition that may increase a woman's risk for developing metabolic and cardiovascular disease during the postmenopausal years. Presently, there is a lack of information on physiological changes during the menopause transition that may predispose to increased disease risk. This study was undertaken to examine changes in energy expenditure, body composition, fat distribution and insulin sensitivity during the menopause transition. Changes in these variables during the menopause transition may have far-reaching consequences for the development of cardiovascular and metabolic disease in women during the postmenopausal years. To accomplish our goal, 60 premenopausal women will be evaluated annually for five years. Body composition, fat distribution, daily energy expenditure and its components and insulin sensitivity will be measured on each visit. The temporal sequence of changes in these variables will be evaluated in those women who traverse the menopause transition (i.e., women who experience menopausal changes) and women who remain premenopausal (i.e., age-related changes).